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AMD Tonga GPU Has 2,048 Cores, but Radeon R9 285 Won't Use Them

The processor also boasts 128 TMUs, according to the block diagram

Aug 13, 2014 07:10 GMT  ·  By
AMD Tonga GPU diagram
   AMD Tonga GPU diagram
Advanced Micro Devices may have launched the FirePro W-Series professional graphics cards, but that doesn't really help everyone who was rooting for a new “normal” video board. It doesn't really help that the Sunnyvale, California-based company is supposed to have prepared a new GPU called Tonga.

However, it turns out that AMD did release some information on this particular graphics processing unit. It was sent out to some web entities at the same time as the Quadro W press kit.

Apparently, the W7100 is powered by the Tonga graphics chip, the same GPU said to be at the heart of the AMD Radeon R9 285.

We didn't immediately spot this because the W7100 chip only has 28 of the 32 compute units active, meaning that it uses only 1,792 stream processors instead of the full 2,048.

Which brings us to the main topic: the core count has been confirmed. There are 2,048 Graphics Corenext 1.1 stream processors in the Tonga GPU, distributed across 32 CUs.

There are 128 texture mapping units as well, TMUs for short, plus a memory interface of 256 bits, which goes well with the 2 GB of the Radeon R9 285. Same for the 8 GB of the W7100.

Most of this information is corroborated by the block diagram in the picture up on the right. You can see there the 256-bit interface, the 32 ROPs (raster operating units), the TrueAudio DSP, and even a modern XDMA CrossFire interface.

This does bring up another point though: contrary to our assumptions about the Radeon R9 285, the board probably won't have all 2,048 SPs activated. Instead, it will use only 1,792, like the Quadro W7100.

Even so, though, it should be able to match the NVIDIA GeForce GTX 760 in terms of performance, power use, and price ($230 - $250 / €230 - €250).

That only leaves the question of what consumer video board will use the Tonga at full power. So far, we've only heard about the Radeon R9 285, but if this latest report is true and AMD could make a much stronger adapter based on it, we can't dismiss the odds of a Radeon R9 285X or some other X-branded model. Such a card would probably also have 4 GB of GDDR5 instead of 2 GB.

We can only wait and see at this point. And the wait probably won't be too short. AMD isn't going to have a visible presence at IFA 2014, in early September, so we can already discount a back-to-school high-end video card release.